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2 years ago

To the nearest tent what is the area of circle whose diameter is 21 inches

Mathematics

1 answer:

xxMikexx [17]2 years ago

8 0

Answer:

It depends

Step-by-step explanation:

Area of a circle is given by

A = pi *r^2

We can find the radius by taking 1/2 of the diameter

r= 1/2(21)

r = 10.5

A = pi * (10.5)^2

A = 110.25 pi

Approximating pi with 3.14

A = 110.25 * 3.14

A =346.185 in^2

To the nearest tenth

A = 346.2 in^2

If we use the pi button on the calculator

A = 346.3605901

Rounding to the nearest tenth

A = 346.4 in^2

You need to determine whether you approximate pi by 3.14 or use the pi button on your calculator

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G find the area of the surface over the given region. use a computer algebra system to verify your results. the sphere r(u,v) =

Svetach [21]

Presumably you should be doing this using calculus methods, namely computing the surface integral along $\mathbf r(u,v)$ .

But since $\mathbf r(u,v)$ describes a sphere, we can simply recall that the surface area of a sphere of radius $a$ is $4\pi a^2$ .

In calculus terms, we would first find an expression for the surface element, which is given by

$\displaystyle\iint_S\mathrm dS=\iint_S\left\|\frac{\partial\mathbf r}{\partial u}\times\frac{\partial\mathbf r}{\partial v}\right\|\,\mathrm du\,\mathrm dv$

$\dfrac{\partial\mathbf r}{\partial u}=a\cos u\cos v\,\mathbf i+a\cos u\sin v\,\mathbf j-a\sin u\,\mathbf k$
$\dfrac{\partial\mathbf r}{\partial v}=-a\sin u\sin v\,\mathbf i+a\sin u\cos v\,\mathbf j$
$\implies\dfrac{\partial\mathbf r}{\partial u}\times\dfrac{\partial\mathbf r}{\partial v}=a^2\sin^2u\cos v\,\mathbf i+a^2\sin^2u\sin v\,\mathbf j+a^2\sin u\cos u\,\mathbf k$
$\implies\left\|\dfrac{\partial\mathbf r}{\partial u}\times\dfrac{\partial\mathbf r}{\partial v}\right\|=a^2\sin u$

So the area of the surface is

$\displaystyle\iint_S\mathrm dS=\int_{u=0}^{u=\pi}\int_{v=0}^{v=2\pi}a^2\sin u\,\mathrm dv\,\mathrm du=2\pi a^2\int_{u=0}^{u=\pi}\sin u$
$=-2\pi a^2(\cos\pi-\cos 0)$
$=-2\pi a^2(-1-1)$
$=4\pi a^2$

as expected.

6 0

2 years ago

Necesito encontrar expresiones equivalentes a los valores del 1 al 20 pliss

Mariulka [41]

Answer and Step-by-step explanation:

Si está buscando una expresión que sea igual a los números del 1 al 20, intente hacer una. Por ejemplo, 2y + 1x = 18 donde y = 9 - x / 2 y x = 18 - 2y. Siempre que la expresión sea igual a menos de 20, ¿no?

Lo siento, no entendí muy bien la pregunta, ¡pero espero que esto te haya ayudado! ¡Ten un día maravilloso! <3

**Tenga en cuenta que mi español no es el mejor, lo siento mucho, hablo principalmente inglés. Mi mal, con suerte, me puedes entender.**

4 0

2 years ago

the results of a poll indicate that between 33% and 37% of the population of a town visit the library at least once a year. what

Vera_Pavlovna [14]

The margin of error is ±2%

<h3>What is Margin error?</h3>

A margin of error is a statistical measurement that accounts for the difference between actual and projected results in a random survey sample.

Let x be margin of error and y be the percentages of the population.

So,

y-x =33%

y +x = 37%

Solving above equations

2y= 70

y= 35%

and x= 2%

Hence, the margin of error is ±2%.

Learn more about this concept here:

brainly.com/question/11421935

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